naimouasta Posted March 26, 2011 Share Posted March 26, 2011 08 2.5i here. i know a lot of you guys don't rely on the MPG gauge but general consensus is its about ~1mpg more than actual. anyway for me i think the gauge is pretty consistent even if its not accurate. when i first got my car new i would average 28.5 consistently in the warmer weather and 26.7 when the winter gas hits. i use Trip A for gas mileage (~300mi), and Trip B for oil change (~5000mi), and MPG readings for both Trip's were the same all the time. this past summer i did a bunch of regular maintenance (plugs, coolant, air filter, etc). now up until about early last winter my gas mileage took a dip. it was random from between 19-21mpg. my driving habits didn't change nor did my gas station. i just cleaned my PCV valve recently which btw was not clicking at all, but cleaned up well. gas mileage jumped up to a solid 24.3 within the last 600mi which is better but i think theres still a little bit MPG left on the table. so my question is, can a bad thermostat cause bad gas mileage? i noticed too that the temp (i know the gauge sucks) gauge gets up to normal temp slower than it used to. i usually warm the car for ~1min then drive slowly til it gets up to temp. usually by the first corner of my development, i can feel a little heat from the vents and the gauge has already started moving, not anymore. now it takes a good 10mins for it to get to normal temps. before it was more like 5-6mins. maybe its stuck slightly open? and is this even possible to have a bad thermostat on a car with 72k miles? i figure most people change their thermostat when they change their timing belt etc @ 105k and most of the time its fine. Link to comment Share on other sites More sharing options...
mcalkins3 Posted March 26, 2011 Share Posted March 26, 2011 I assure your not crazy!! A lower coolant temp will cause worse fuel mileage as the ECM is running rich until operating temp has been reached! Link to comment Share on other sites More sharing options...
iNVAR Posted April 3, 2011 Share Posted April 3, 2011 +1. And thermostat lifespans can vary. Link to comment Share on other sites More sharing options...
naimouasta Posted April 4, 2011 Author Share Posted April 4, 2011 i'll change it once it gets a little warmer. i'll probably drain and fill some new coolant once that time comes too. weird but a couple nights ago, i beat the crap out of my car for like 5 mins LOL. after that gas mileage started climbing again and the temps now warm up as usual. must have cleared out some cobwebs or something LOL. Link to comment Share on other sites More sharing options...
Gasaraki Posted April 10, 2011 Share Posted April 10, 2011 Some people say it's ok to WOT your car once in awhile. It's cleans out the cobwebs. Link to comment Share on other sites More sharing options...
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